Litsea cubeba Essential Oil Reduces Postharvest Blueberry Rot by Inducing Cell Membrane Damage and Reactive Oxygen Species Accumulation in Alternaria alternata

Abstract

Fruit rot caused by Alternaria alternata infection is one of the primary diseases responsible for postharvest losses in blueberries. Litsea cubeba essential oil (LCEO) exhibits potent control efficacy against A. alternata, but its antifungal mechanisms and effects on the postharvest quality of blueberries remain unclear. In vitro text showed that LCEO treatment induced severe developmental and hyphal morphology impairments of A. alternata. Treatment with 2×MFC LCEO notably reduced blueberry fruit rot incidence while decreasing fruit respiration rate and maintaining fruit quality such as higher fruit weight, firmness, total soluble solids, total acidity, total phenolic, and flavonoid. Mechanistic studies revealed that LCEO treatment severely impaired the cell membrane integrity of A. alternata mycelium, manifesting as markedly increased intracellular propidium iodide (PI) fluorescence intensity, pronounced intracellular solute leakage, and increased extracellular electrical conductivity. However, LCEO treatment did not alter cell wall calcofluor white (CFW) fluorescence intensity and alkaline phosphatase activity. Additionally, LCEO application triggered a sharp and sustained increase in ROS accumulation and consequent lipid peroxidation, while leading to a progressive decline in mitochondrial membrane potential. Therefore, LCEO exerts its antifungal activity by impairing the normal growth and development of A. alternata through multi-target damage, thereby reducing postharvest rot losses in blueberries.